1. Field of Invention
The present invention relates to a display panel driving device and a driving method thereof. More particularly, the present invention relates to a display panel driving device using a single gamma curve and a driving method thereof.
2. Description of Related Art
Currently, in order to improve display quality and provide grayscale levels of each primary color that can be accurately sensed by the eye, gamma curves are usually used to relate the grayscale levels of each primary color to driving voltages required by display devices. FIG. 1 is a curve diagram showing gamma curves of each primary color of an organic light-emitting diode (OLED), wherein the horizontal axis stands for grayscale level and the vertical axis stands for voltage. A red light gamma curve 101 almost overlaps a blue light gamma curve 102, which are shown by one common curve in FIG. 1, while a green light curve 103 is apparently different from the curves 101 and 102. FIG. 2 shows a circuit block diagram of a conventional OLED display 200. The OLED display 200 comprises a source driver 21, an OLED panel 22 and a gate driver 23. The source driver 21 receives data and three groups of gamma voltages of red light, green light and blue light, wherein the three groups of gamma voltages are sampled values from the red, green and blue primary color gamma curves, respectively. The source driver 21 converts grayscale levels of three primary colors in the input data into three groups of driving voltages with reference to the red light, green light and blue light gamma voltages, and then outputs the three groups of driving voltages to the OLED panel 22. The OLED panel 22 is sequentially scanned by the gate driver 23 controlled by the input signal. As three groups of gamma voltages are needed, the complexity of the circuit is greatly increased and the development time of the product is prolonged so that there is a risk of revealing secrets during the long product research/development process.
FIG. 3 shows a circuit block diagram of another conventional OLED display 300. The OLED display 300 comprises a source driver 31, an OLED panel 32 and a gate driver 33. Data are input into the source driver 31 by an external device (not shown), and the grayscale levels of red light, green light and blue light in the input data are converted into driving voltages by the source driver 31 according to a single group of gamma voltages of a single gamma curve and then the driving voltages are input into the OLED panel 32. The gate driver 33 receives a control signal to sequentially scan the OLED panel 32. Referring to both FIGS. 1 and 3, as the source driver 31 generates driving voltages of each primary color according to a single gamma curve, for example, assume the single gamma curve is the red light gamma curve 101, the driving voltage may be too high for the green light when the input data represents an all white frame, thereby resulting in a greenish frame. On the other hand, if the single gamma curve is the green light gamma curve 103, the driving voltages are apparently insufficient for the red light and the blue light when the input data represents an all white frame, also resulting in a greenish frame.